//题目：练习函数调用
#include<stdio.h>
    void hello_world(void)
    {
        printf("Hellow,world!\n");
    }
    void three_hellos(void)
    {
        int counter;
        for(counter=1;counter<=3;counter++)
        hello_world();
    }
    void main(void)
    {
        three_hellos();
    }